What is the transponder code for lost communication?

The transponder code used for lost communication is 7600. This specific code is universally recognized as a signal that an aircraft is experiencing radio communication issues. When a pilot sets their transponder to 7600, it alerts air traffic control that they cannot communicate with them, and they may need to take special considerations to maintain safety while the aircraft continues its flight.

In contrast, different transponder codes serve other purposes: 7500 is reserved for indicating unlawful interference, such as a hijacking. 7700 signifies an emergency situation that does not necessarily relate to communication failure, such as medical emergencies or aircraft malfunctions. 7800 is not a standard code used in aviation. Each of these codes has a distinct meaning, and knowing them helps ensure proper communication and response among pilots and air traffic controllers.